Olefins, for example alpha-olefins, referred to as 1-olefins, have many uses. In addition to uses as specific chemicals, alpha-olefins are used in polymerization processes either as a monomer or a comonomer to prepare polyolefins, or polymers. Higher alpha-olefins and other olefins can be produced by contacting lower olefins, for example ethylene, with a catalyst, producing trimers of mono-olefins, dimers of diolefins, or other reaction products in an addition reaction. This reaction or addition of two or more olefins is generally referred to as oligomerization. Trimerization, which is the addition of three olefins, is a subset of the general class of oligomerization reactions. Often, the catalyst system is dispersed in a process solvent, and the reactants, a lower 1-olefin and optionally hydrogen, are fed in as gases. The reaction product or higher olefins dissolve in the process solvent as they are formed. Product olefins and catalyst are removed from the reactor in the process solvent containing them, i.e., in the oligomerization reactor effluent.
Unfortunately, during the production of olefins, a significant reaction co-product can be a polymeric material. Polymer production during the course of olefin preparation is detrimental to the process and reactor because polymer can build up on the interior walls or other portions of the reactor and inhibit heat transfer. Furthermore, any polymer produced needs to be separated from the olefin products stream, and/or a low molecular weight polymer can be formed causing a sticky, glue-like substance throughout the process and reactor.
To prevent polymer formation and potential buildup in that part of the process downstream of the oligomerization reactor resulting from active catalyst in the reactor effluent, systems to deactivate catalyst activity have been developed. In addition to prevention of polymer formation, deactivation of the catalyst system is important to prevent isomerization of the 1-olefin product to undesirable internal, i.e., 2- and higher, olefins, which lowers the product purity. Deactivation of the catalyst system also can remove hazards associated with the air- and water-sensitivity of aluminum alkyls.
There exists a need, therefore, for a deactivation process for use with halide-containing oligomerization catalyst systems, for example, metal halides such as alkylaluminum halide, which reduces or eliminates downstream corrosion.